Our invention provides volatile substance-emitting apparatus and methods for producing same and for using same wherein the volatile substance can be an air freshener, standard aromatizing material, odor maskants, insecticides, insect repellants, animal repellants, herbicies, pheremones and the like. These volatile substances have previously been used with the following delivery systems:
aerosols;
gels;
paper;
felt;
large pore polymers;
powders;
candles; and
wick-containing liquids.
With the exception of aerosols, the concentration and rate of release of volatile substance, e.g., perfume, into the atmosphere surrounding the container or emitting apparatus has been a function of the rate of evaporation of volatile material which, in turn, has been a function of the remaining concentration of volatile material in the container or emitting apparatus. Accordingly, the rate of mass transfer (e.g., diffusion in certain instances) of the volatile substance into the surrounding atmosphere has, in the prior art, been "first order", that is, a function of the concentration previously present, e.g.: ##EQU1##
Furthermore, with respect to the apparatus of the prior art there has been no practical way for ascertainment by the user as to whether or not the bulk of the volatile material has been depleted at a particular point in time. In all instances it is impossible to determine precisely when the volatile substance is no longer being discharged in an effective quantity and/or concentration per unit time into the atmosphere surrounding the container. In those situations where an aroma is being emitted, the actual aroma is usually relatively powerful during the emission notwithstanding the rate of emission of active agent and said aroma retains its power even after its practical effect (e.g., air freshening) is deminimis.
Thus, in Japanese Pat. No. J8-0036,515 assigned to Akane Soji K K, printings from which fragrance is gradually emitted are indicated to be produced by a process comprising (1) preparing fragrance-emitting ink compositions by dispersing (a) fragrance-emitting bases prepared by mixing perfume solutions with thermoplastic resins at elevated temperatures to homogenize the mixture, followed by cooling the mixture to separate fine particles of gelled resin in which the perfume is occluded in (b) a solution of film-forming material and (2) printing the base material with this fragrance-emitting ink composition.
Scent-releasing polyurethane foams are shown to be prepared in German published Application No. 2,945,757 (assigned to the Tenneco Chemical, Inc.). In published Application No. 2,945,757, it is indicated that a polyurethane foam containing a particulate filler and perfume is prepared by first mixing the filler with the perfume and adding this mixture to a liquid polyol and finally mixing the thus-obtained composition with an organic polyisocyanate, water and a catalyst to produce the resulting foam. It is indicated that the resulting material is used as an air freshener, deodorant, perfume sachet and the like. It is further indicated that the foam releases the perfume at a limited and constant rate. The said published German Application corresponds to U.S. Pat. No. 4,226,944 issued on Oct. 7, 1980.
U.S. Pat. No. 4,247,498 issued on Jan. 27, 1981 discloses a method for preparing a homogeneous microporous cellular polymer structure which evolves perfumes, insect repellants, odor masking agents and the like at a slow and steady rate. The process of U.S. Pat. No. 4,247,498 comprises (i) heating a mixture of a polymer which may be an olefinic polymer, condensation polymer, oxidation polymer or a blend thereof and a "compatible liquid" to a temperature and for a time sufficient to form a homogeneous solution, (ii) forming at substantially the same time a plurality of liquid droplets of substantially the same size in a continuous liquid polymer phase by cooling the solution, (iii) continuing cooling to solidify the polymer, (iv) then at least partially displating the "compatible liquid" with a perfume, an odor masking agent, an insect repellant or the like. It is indicated at column 15, line 30 of U.S. Pat. No. 4,247,498 that the disclosed system may be used to create a "thin film of about 1 mil or less up to a relatively thick block of thickness of about 21/3 inches".
Japanese published Application No. J5-5081,655 assigned to Kureha Chemical Industries KK discloses a slow release air aromatizing composition which comprises an aqueous solution of water soluble high molecular weight substance of viscosity 500-30,000 cps such as polyvinyl acetate, carboxymethyl cellulose, sodium alginate, xanthan gum, etc. admixed with an oil soluble perfume or a water soluble perfume.
Nothing in the prior art, however, discloses the novel structure and process for preparing same of our invention wherein a commercially viable structure capable of dispensing at a steady state, at a visibly detectable rate either continuously or discontinuously for discrete periods of time, a volatile composition of matter such as a perfume, an air freshener, an air deodorant or the like, is created.